In a solid state drive (SSD), the SSD must go through an orderly shutdown in the event of a loss of power to prevent corruption or loss of data. In particular, in the event of a loss of power, the SSD must complete all in progress data writes and provide a controlled shutdown of the media and firmware. Modern SSDs may include a power loss system that provides sufficient energy to complete these in process data writes and allow for a controlled shutdown of the SSD. For example, a set of power loss capacitors may be used to provide sufficient energy storage to provide power for shutdown operations in the event of a loss of power.
During operation, the SSD may periodically test the power loss capacitors. For example, the SSD may periodically measure the capacitance of the power loss capacitors to determine whether the capacitance has degraded. If degradation is detected, a notification can be made to a host system coupled to the SSD to alert the host system that the power loss capacitors may have insufficient energy storage to protect data integrity in the event of a loss of power.
Testing the power loss capacitors may be facilitated by discharging the capacitors using a known load. The discharge may be measured for a specific voltage drop or for a specific discharge time. Discharging the capacitors using a known load lowers the voltage of the capacitors below their normal operating range. As such, current SSD power loss capacitors must be sized such that their minimum operating voltage, even during testing, is sufficient to protect data integrity in the event of a loss of power.